Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Pat the chicken breast dry with a paper towel and cut it into bite-sized 1-inch cubes.
Drain and rinse the chickpeas, then pat them very dry with a clean kitchen towel to ensure they get crispy in the oven.
Place the chicken, chickpeas, broccoli florets, and chopped red bell pepper onto the prepared baking sheet.
Drizzle with olive oil and sprinkle evenly with sea salt, black pepper, garlic powder, and smoked paprika.
Toss everything together until well-coated, then spread into a single layer so the ingredients roast rather than steam.
Roast in the oven for 18 to 20 minutes, or until the chicken is cooked through and the chickpeas have a slight crunch.
While the bowl base roasts, whisk together the tahini, lemon juice, and Dijon mustard in a small bowl, adding a teaspoon of water at a time until it reaches a pourable consistency.
Transfer the roasted mixture to a bowl and drizzle the zesty tahini dressing over the top before serving warm.